The present invention relates to a semiconductor device, and more particularly, to a method of manufacturing a semiconductor device using a support pattern which supports the bottom plate of the capacitor in order to prevent a capacitor leaning phenomenon in the dip-out process.
Generally, the cell of the DRAM (Dynamic Random Access Memory) includes a capacitor for storing a charge, and a transistor that addresses the charge stored in the capacitor. As usual, the transistor that is formed on a semiconductor substrate includes a gate electrode that controls the flow of current between source/drain regions. The charge which is stored in the capacitor is accessed through the transistor.
Currently, as the integration density of semiconductor devices has increased, the area of the memory cell has also decreased considerably. In addition, as the memory cell area has decreased, the capacitor area that forms the memory cell has also decreased. Considering the read-out of cells, the soft error due to alpha particles, and the sensing margin of a sense amp, the capacitance should be 25 fF or more so that a DRAM might operate normally. The capacitance is in proportion to the dielectric constant of a dielectric that exists between the surface area of the electrode and the electrode.
The capacitance of capacitor can be expressed by the following Equation 1. In this case, ∈ is a dielectric constant determined by the kind of dielectric layer that is positioned between two electrodes, d is a distance between two electrodes, and A indicates an effective surface area of two electrodes. As shown in Equation 1, as the dielectric constant ∈ of the dielectric layer is increased, as the distance d between two electrodes is decreased, and as the surface area A of two electrodes is increased, the capacitance of a capacitor is increased.
                    C        =                  ɛ          ⁢                      A            d                                              [                  Equation          ⁢                                          ⁢          1                ]            
Accordingly, recently, a three dimensional capacitor electrode structure such as the concave structure, or the cylinder structure has been developed so as to enhance the effective area of a electrode.
The capacitor having the concave structure is formed, after forming a hole on an interlayer insulating layer, forming a bottom plate of a capacitor on the inside surface of the hole, and sequentially laminating the dielectric layer and a top plate on the surface of the bottom plate. However, it has been hard to secure enough electrostatic capacity which is required per cell in the limited cell area with the capacitor of the concave structure as the semiconductor device becomes more highly integrated. Therefore, the capacitor of the cylinder structure capable of providing the surface area which is greater than the capacitor of the concave structure was suggested.
In order to form the capacitor of the cylinder structure, a contact hole is made on the interlayer insulating layer, and the interlayer insulating layer is removed after the bottom plate of a capacitor is formed inside the contact hole, and then, the dielectric layer and the top plate are sequentially laminated onto the surface of the remaining bottom plate. The capacitor of the cylinder structure can use both of the inside and the outer surface of the bottom plate as the effective surface area of a capacitor. Therefore, the capacitor of the cylinder structure can have the electrostatic capacity which is greater than the capacitor of the concave structure.
In order to form the capacitor of such a cylinder structure, the dip-out process is essential, the dip-out process is performed with the wet method including a chemical solution.
However, the chemical solution causes a phenomenon where the structure of the cylinder type leans or collapses in the dip-out process. Particularly, in the case where the aspect ratio of the bottom plate for the storage node is large due to the integration level of the semiconductor device, the leaning and collapsing becomes conspicuous.